1. Field
The present application relates generally to the operation of data networks, and more particularly, to methods and apparatus for RF channel switching in a multi-frequency network.
2. Background
Data networks, such as wireless communication networks, have to trade off between services customized for a single terminal and services provided to a large number of terminals. For example, the distribution of multimedia content to a large number of resource limited portable devices (subscribers) is a complicated problem. Therefore, it is important for network operators, content retailers, and service providers to have a way to distribute content and/or other network services in a fast and efficient manner and in such a way as to increase bandwidth utilization and power efficiency.
A multi-frequency network (MFN) is a network in which multiple radio frequencies (RFs) (or RF channels) are used to transmit media content. One type of MFN is a horizontal multi-frequency network (HMFN) where a distribution waveform is transmitted over different RF channels in different local areas. The same or different content may be transmitted as part of distribution waveforms carried over different RF channels in such local areas. Another type of MFN is a vertical multi-frequency network (MFN) in which multiple radio frequency (RF) channels are used in a given local area to transmit independent distribution waveforms with an aim to increase the capacity of the network (in terms of the ability to deliver more content to a device/end user). An MFN deployment may also consist of VMFN in certain areas and HMFN in certain other areas.
A typical VMFN comprises multiple distribution waveforms each comprising one or more content flows that can be selected by a device user for viewing. Additionally, information is provided with each distribution waveform that allows a receiver to determine the characteristics (e.g., Transmission Mode, Reed-Solomon coding, etc) of individual flows being transmitted. This information may be contained in a separate control channel. Before a receiver can decode flows carried by a particular distribution waveform, it needs to know these characteristics, and hence, it needs to decode the control channel.
Therefore, given the VMFN case described above, it will be assumed that two independent distribution waveforms are available on different RF channels. A receiver switching from a first RF channel to a second RF channel to receive additional flows will therefore incur the delay of having to acquire the control channel on the second RF channel. Once it does so, it can decode the information it needs to start decoding the flows on the second RF channel. Unfortunately, the time it takes to switch to the second RF channel and acquire the control channel information may increase channel switching time as perceived by the device user, and therefore may result in an unsatisfactory user experience.
Additionally, since the control channel also carries dynamic information about whether or not a content flow is present and its RF channel location, a receiver interested in receiving a particular content flow needs to periodically monitor the control channels on all RF channels used by the network to determine the location (i.e., RF channel) of the desired content flow. However, monitoring all RF channels can have a negative impact on device operation by causing an interruption of flows currently being decoded or by causing the acquisition of a flow to be missed. Furthermore, even if a receiver attempts to monitor all RF channels there is no guarantee that the information it acquires from one RF channel won't become stale while the receiver is monitoring other RF channels.
Therefore, it would be desirable to have a system that operates to quickly and efficiently identify the RF channel associated with a particular content flow and thereby facilitate fast channel switching capabilities in a vertical multi-frequency network.